I'd be curious to know if distance is a factor they accounted for. Traffic in LA is straight-up gridlock (or at least it was when I lived there). You could spend an hour going 10 miles, and that's not even during commute hours.

If you spend 90 minutes driving from SF to Mountain View, traffic definitely makes it slower/worse than it would otherwise be, but it'd still be a 45 minute drive without traffic.

People may spend more time driving in SF/SV, but that's largely a factor of how far apart desirable housing and jobs are for many people. I wouldn't be surprised if traffic on the Peninsula made commutes 2-3x longer than they'd be without it, but in LA the factor's more like 6x.